Electrical condenser



Mardl 8, 1950 A. .T. CHAPMAN 2,502,310

ELECTRICAL CONDENSER Filed March 16, 1946 M/ vs/vro/v A. 7.' CHAPMAN ATTORNEY Patented Mar. 28, 1950 ELECTRICAL CONDENSER Alan T. Chapman, Clifton, N. J., asslgnor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application March 16, 1946, Serial No. 54,930

4 Claims. 1

This invention relates to electrical condensers, and more particularly to electrical condensers designed to be potted in metal cans.

Assembled and functionally complete condenser units are frequently placed in metal cans and the interstices of their structure then filled with some suitable molten insulating and waterpoof compound to render the condensers substantially immune to meteorologic changes and to protect them against mechanical injury, particularly from shock and vibration. Such core assemblies ordinarily have metal members exposed at their outer surfaces, which may be more or less intensely electrically charged in use.

An object of the present invention is to provide a condenser core assembly provided with simple reliable means to cover and protect the metal elements of the assembly against contact with a close fitting metal container therefor, the protective means being of such character as to be not materially altered or injured by the possibly intense, high frequency electrical stresses to which the means or parts thereof may be subjected when the condenser is in use.

With the above and other objects in view, the invention may be illustratively embodied in an electrical condenser and a protective metal con tainer therefor in combination with an insulating sheath for the condenser and interposed between the condenser and the container, the said sheath comprising a sheet of flexible mica wrapped about the condenser.

Other objects and features of the invention will appear from the following detailed description of an embodiment thereof taken in connection with the accompanying drawing in which the same reference numerals are applied to identical parts in the several figures and in which Fig. 1 is a plan view partly in section of a structure embodying the invention; and

Fig. 2 is a front view thereof with parts broken away.

The assembly herein disclosed is a unitary combination of three suitably conjoined individual condensers. There are three central dielectric sheets IO, N and I2, preferably each an integral oblong lamina of mica. On each face of these is a metallic coating, l4 and IS on I0, I6 and I I on II, and I8 on I9 on I2. In the case of the mica lamina I0, for example, the coating It on the far side of the lamina extends out to the right hand edge; but there is a peripheral strip of bare mica at top and bottom and along the left edge; while the coating l5, symmetrically disposed, extends to the left edge of the mica,

te'cting material.

but not to the top, bottom or right edges. The coatings I6 and I! are respectively reversely disposed on the lamina II, while the coating I8 and H! have the same arrangement on the lamina I2 as the coatings on H). These six coatings may be of any suitable metal, preferably of silver.

At each end of the lamina ID, a sheet metal connecting clamp is folded over about and clamped on the vertical edge portion of the lamina and of the coating which extends out to that edge, but is too narrow to reach to and make contact with the other coating. Thus the clamp 20 makes contact with the coating I5 but not with the coating I4, while the clamp 2| makes contact with the coating I4 but not with the coating I5. Similarly, of the two clamps on the lamina II, clamp 22 contacts coating I6 but not coating ll, while clamp 23 contacts coating II but not coating l6. And on lamina I2, clamp 24 contacts coating I9 but not coating I8, while clamp 25 contacts coating I8 but not coating I9. These six clamping members 20, 2|, 22, 23, 24 and 25 may be of any suitable metal, preferably brass. Additionally, each of the clamps 24 and 2| is provided with an integral upstanding terminal arm 26 and 21 respectively.

In assembling these three component condensers, they are stacked together in registration side by side, and the clamps 20 and 22 are 501- dered together as indicated at 28, while the clamps 23 and 25 are soldered together as indicated at 29. While this is being done, the clamps 2| and 23 are ordinarily held in contact as are also the clamps 22 and 24. The soldering having been completed and the heated portions cooled down, the clamps 2| and 23 are sprung apart sufficiently to introduce the end edge of a laminar' sheet or ribbon 30 of flexible, insulating and pro- Similarly, the clamps 22 and 24 are sprung sufiiciently apart to insert between them the end portion of a similar sheet or ribbon 3|. The sheets 30 and 3| are then wrapped around the condenser assembly and about each other, being dimensioned to provide whatever partial or complete or plural overlapping i preferred in a particular instance. The whole assembly is then inserted into a can or casing 32 of suitable metal, e. g. aluminum or tinned iron, being held together for insertion by the fingers or with some suitable binding means, e. g. a length of thread or of adhesive tape.

The discovery and provision of suitable material for the tapes 30 and 3| is a crucial feature of the invention. Ordinary mica, such as i used for the laminae IO, N and I2, would be ideal, but

is too brittle. It cannot be bent around the corners. Other flexible materials, e. g. textiles, paper and the like, either alone or impregnated in various ways, all prove to be unsatisfactory in various ways. Some are too hygroscopic: some are brittle, some give oi! minute but chemically corrosive amounts of vapors; etc.

It has been discovered that what is colloquially termed "flexible mica," when suitably prepared, can be used for the material of the tapes III and Ii, satisfactorily. Flexible mica is made from the extremely thin flakes of mica which are a byproduct or waste material from the processes of splitting and cutting mica slabs to make, for example, such articles as the laminae III, II and I2. Such flakes may have surface dimensions of the order oi a large fraction oi an inch, say upward of inch, but a thickness dimension of the order of one or perhaps two thousandths of an inch. Several or many layers of such flakes in overlapping juxtaposition, asmany as may be required for a particular purpose, are bound together with a minimum amount of a suitable adhesive. For the present purpose, an eminently suitable adhesive bonding material is shellac. Another suitable bonding substance may be rosin softened with rosin oil. Such bonding materials form a flexible mica sheet quite sufllciently flexible for present purposes when used reasonably soon after preparation of the sheet and are chemically substantially inert to the brass oi. the clamps II and 24, to the silver of the coatings ll to i9, and to the aluminum or tinned iron of the can 32. Such material tends to become brittle and inflexible with age; but this is no detriment. for preesnt purposes, after the ribbon has been wrapped and given its final, permanent form. In some instances, if desired, when shellac is used as the bonding agent, a modicum of a suitable plasticizer, e. g., glycerol, castor oil, or the like, may be added to delay or inhibit brittleness.

What is claimed is:

1. The combination with a plurality of electrical condensers placed side by side each having a clamp at each end, and a protective metal container for said condensers, of an insulating sheath tor the condensers interposed between the condensers and between the condensers and the container, the said sheath comprising a sheet of flexible mics, and having an end anchored between two adjacent clamps.

2. The combination with a pluralit of electrical condensers placed side by side each having a clamp at each end, and a protective metal container for said condensers, of an insulating sheath for the condensers interposed between the condensers and between the condensers and the container, the said sheath comprising a sheet of flake mica bonded with an insulating adhesive inert to the materials of the condenser and container, and having an end anchored between two adiacent clamps.

3. The combination with a plurality oi electrical condensers placed side by side each having a clamp at each end, and a protective metal container for said condensers, of an insulating sheath tor the condensers interposed between the condensers and between the condensers and the container, the said sheath comprising a sheet of flake mica, bonded with shellac, and having an end anchored between two adjacent clamps.

4. The combination with a plurality of electrical condensers placed side b side each having a clamp at each end, and a protective metal container for said condensers, of an insulating sheath for the condensers, interposed between the containers and between the condensers and the container, the said sheath comprising a sheet of flake mica, bonded with shellac and a plasticizer therefor, and having an end anchored between two adjacent clamps.

ALAN T. CHAPMAN.

REFERENCES CITED The following references are of record in the die 01' this patent:

UNITED STATES PATENTS Number Name Date 389,519 Lee Sept. 11, 1888 1,317,204 McCoy Sept. 30, 1919 1,870,803 Fried Aug. 9, 1932 1,999,874 Hartzell Apr. 30, 1935 2,136,609 Butteriield Nov. 15, 1938 

